1. Field of the Invention
The present invention relates generally to a transfer apparatus for transferring a carrier loaded with a number of objects such as printed circuit boards. More particularly, the present invention relates to a carrier transfer apparatus for unloading and/or loading semiconductor device packages from and/or to printed circuit board loaded in the carrier.
2. Description of the Related Arts
The semiconductor chip package manufactured by a complex assembly process is subjected to various tests including thermal (e.g., bum-in and Temperature Cycling tests) and electrical tests to assure its reliability. Semi conductor packages are tested in mass using a printed circuit board carrying a plurality of packages.
The terms employed throughout this application `unloader/loader`, and `carrier` will be described hereinafter.
The term `unloader/loader` indicates a means for loading or unloading a semiconductor device package into or from a printed circuit board, and vice versa; and the term `carrier` indicates a container which is capable of carrying a plurality of printed circuit boards.
Package reliability tests include, for example, the following steps (1) through (4):
(1) The packages are stored in a warehouse in a storage container unit such as a tube or tray. The containers carrying the packages, and printed circuit boards are manually transferred to an unloader/loader working area, where the packages are unloaded from the container and loaded to the printed circuit boards.
(2) The printed circuit boards loaded with a plurality of packages are manually mounted in a carrier placed on a cart, and then moved to a test equipment. The carrier carrying the printed circuit boards is manually loaded onto the test equipment and the packages in the printed circuit boards are subjected to thermal and/or electrical tests.
(3) After completion of the tests, the printed circuit boards are manually removed from the test equipment and loaded in the carrier on the cart. Then, the carrier is moved to the unloader/loader working area.
(4) At the unloader/loader working area, the printed circuit boards are removed from the carrier, and the packages are unloaded from the printed circuit board and mounted in the storage container. The storage container carrying the packages is moved to and stored at the warehouse. Good packages are stored, while the failed packages are destroyed.
In the conventional carrier transfer process described above, the steps of unloading and loading the packages and the printed circuit boards are carried out manually and have the following drawbacks: First, since the loading/unloading of the package into/from the printed circuit board is carried out manually at the printed circuit board level, the productivity varies depending on the skill; speed and efficiency of a particular worker; and second, since a cart is used to carry the printed circuit boards and is moved to different areas operation space is not efficiently utilized.